Known examples of internally coolable components of the generic type are turbine blades of static gas turbines having, inside them, cooling ducts arranged in a straight or serpentine manner. A turbine blade of this type is disclosed in EP 1 431 514 A2. On the inner surface thereof there are arranged turbulators, also termed cooling ribs, extending largely transversely with respect to the main flow direction of a coolant, for example cooling air. The cooling ribs improve the mixing of the coolant and thus increase the heat transfer from the wall into the coolant. Simultaneously, according to EP 1 431 514 A2, what are termed pins are also provided in a central section of the cooling duct between the cooling ribs and are of different heights depending on their position on the chord and their spanwise position. Both in EP 1 431 514 A3 and in U.S. Pat. No. 7,901,183, the pins connect the suction-side blade airfoil wall to the pressure-side blade airfoil wall.
A disadvantage of this is that the cooling ribs increase the flow resistance and lead to greater pressure losses. If pressure losses are too great, hot gas can be drawn in through cooling air outlet openings through which the coolant is in fact supposed to flow out. This can lead to the destruction of the blade. For this reason, and for reasons of efficiency, the pressure losses arising in the cooling duct should be kept as small as possible.
Usually, the cooling duct cross section and the shape, size, arrangement and distribution of the turbulators are matched such that sufficient coolant pressure can be provided at the cooling air outlet openings, such that hot gas is not drawn in.
There is however still the need to further reduce the pressure losses in the cooling duct of internally cooled gas turbine components.